Wi-Fi, Standards. Wi-Fi standards 802.11 b g what does it mean?

Today we will look at all existing standards IEEE 802.11, which prescribe the use of certain methods and data rates, modulation methods, transmitter power, frequency bands in which they operate, authentication methods, encryption and much more.

From the very beginning, it has been the case that some standards operate at the physical layer, some at the media layer, and others at higher levels of the interaction model. open systems.

The following groups of standards exist:

IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n and IEEE 802.11ac complete the work network equipment(physical level).
IEEE 802.11d, IEEE 802.11e, IEEE 802.11i, IEEE 802.11j, IEEE 802.11h and IEEE standard.
802.11r - environmental parameters, radio frequencies, security features, methods of transmitting multimedia data, etc.
IEEE 802.11f IEEE 802.11c - the principle of interaction between access points, the operation of radio bridges, etc.

IEEE 802.11

Standard IE EE 802.11 was the “first-born” among wireless network standards. Work on it began back in 1990. As expected, this was done by a working group from IEEE, whose goal was to create a single standard for radio equipment that operated at a frequency of 2.4 GHz. The goal was to achieve speeds of 1 and 2 Mbit/s using the DSSS and FHSS methods, respectively.

Work on creating the standard ended after 7 years. The goal was achieved but at a speed. provided by the new standard turned out to be too small for modern needs. Therefore, a working group from IEEE began developing new, faster standards.
The developers of the 802.11 standard took into account the features of the cellular architecture of the system.

Why cell phone? It’s very simple: just remember that waves propagate in different directions over a certain radius. It turns out that the zone looks like a honeycomb. Each such cell operates under the control of a base station, which acts as an access point. A cell is often called basic service area.

So that the basic service areas can communicate with each other, there is a special distribution system (Distribution System. DS). The disadvantage of the 802.11 distribution system is the impossibility of roaming.

Standard IEEE 802.11 provides for the operation of computers without an access point, as part of one cell. In this case, the functions of the access point are performed by the workstations themselves.

This standard was developed and focused on equipment operating in the frequency band 2400-2483.5 MHz. In this case, the cell radius reaches 300 m, without limiting the network topology.

IEEE 802.11a

IEEE 802.11a This is one of the promising wireless network standards, which is designed to operate in two radio bands - 2.4 and 5 GHz. The OFDM method used allows achieving a maximum data transfer rate of 54 Mbnt/s. In addition to this, the specifications provide for other speeds:

• mandatory 6. 12 n 24 Mbnt/s;
• optional - 9, 18.3G. 18 and 54 Mbnt/s.

This standard also has its advantages and disadvantages. The advantages include the following:

• use of parallel data transmission;
• high transmission speed;
• ability to connect a large number of computers.

The disadvantages of the IEEE 802.1 1a standard are:

• smaller network radius when using the 5 GHz band (approximately 100 m): J higher power consumption of radio transmitters;
• higher cost of equipment compared to equipment of other standards;
• Special permission is required to use the 5 GHz band.

To achieve high data rates, the IEEE 802.1 1a standard uses quadrature amplitude modulation technology QAM.

IEEE 802.11b

Working on a standard IEEE 802 11b(another name for IFEE 802.11 High rate, high throughput) was completed in 1999, and the name Wi-Fi (Wireless Fidelity) is associated with it.

Job this standard Based on Direct Spread Spectrum (DSSS) using eight-bit Walsh sequences. In this case, each bit of data is encoded using a sequence of complementary codes (SSC). This allows you to achieve a data transfer rate of 11 Mbit/s.

Like the base standard, IEEE 802.11b operates at a frequency 2.4 GHz, using no more than three non-overlapping channels. The range of the network is about 300 m.

A distinctive feature of this standard is that, if necessary (for example, when signal quality deteriorates, great distance from the access point, various interference), the data transfer rate can be reduced down to 1 Mbnt/s. On the contrary, when it detects that the signal quality has improved, the network equipment automatically increases the transmission speed to the maximum. This mechanism is called dynamic speed shifting.

In addition to IEEE 802.11b equipment. frequently encountered equipment IEEE 802.11b*. The only difference between these standards is the data transfer speed. In the latter case, it is 22 Mbit/s thanks to the use of the binary packet convolutional coding (P8CC) method.

IEEE 802.11d

Standard IEEE 802.11d determines the parameters of physical channels and network equipment. It describes the rules regarding the permitted radiated power of transmitters in the frequency ranges permitted by law.

This standard is very important because network equipment uses radio waves to operate. If they do not meet the specified parameters. This may interfere with other devices. operating in this or a nearby frequency range.

IEEE 802.11e

Since data of different formats and importance can be transmitted over the network, there is a need for a mechanism that would determine their importance and assign the necessary priority. The standard is responsible for this IEEE 802.11e, designed for the purpose of streaming video or audio data with guaranteed quality and delivery.

IEEE 802.11f

Standard IEEE 802.11f designed with a cell to ensure authentication of network equipment ( workstation) when moving the user’s computer from one access point to another, that is, between network segments. In this case, the service information exchange protocol comes into effect. IAPP (Inter-Access Point Protocol), which is necessary for data transfer between access points. In this case, effective organization of the work of distributed wireless networks.

IEEE 802.11g

The second most popular standard today can be considered the standard IEEE 802.11g. The purpose of creating this standard was to achieve data transfer speed 54 Mbit/s.
Same as IEEE 802.11b. The IEEE 802.11g standard is designed to work in frequency range 2.4 GHz. IEEE 802.11g specifies mandatory and possible data rates:

• mandatory -1;2;5,5;6; eleven; 12 and 24 Mbit/s;
• possible - 33;36;48 n 54 Mbit/s.

To achieve such indicators, coding using a sequence of complementary codes (SCS) is used. orthogonal frequency division multiplexing method (OFDM), hybrid coding method (HCC-OFDM) and binary packet convolutional coding method (PBCC).

It is worth noting that the same speed can be achieved different methods, however, the required data rates are only achieved using methods SSK n OFDM, and possible speeds using the SSK-OFDM and RVSS methods.

The advantage of IEEE 802.11g equipment is its compatibility with IEEE 802.11b equipment. You can easily use your computer with network card IEEE standard. 802.11b to work with an IEEE 802.11g access point. and vice versa. In addition, the power consumption of equipment of this standard is much lower than that of similar equipment of the IEEE 802.11a standard.

IEEE 802.11h

Standard IEEE 802.11h designed to effectively control the transmitter radiation power, select the transmit carrier frequency and generate the necessary reports. It introduces some new algorithms to the media access protocol MAS(Media Access Control, media access control), as well as the physical layer of the IEEE 802.11a standard.

This is primarily due to the fact that in some countries the range 5 GHz used for broadcasting satellite television, for radar tracking of objects, etc., which may interfere with the operation of wireless network transmitters.

The meaning of the IEEE 802.11h standard algorithms is this. that when reflected signals (interference) are detected, wireless network computers (or transmitters) can dynamically change bands and lower or increase transmitter power. This allows you to more effectively organize the work of street and office radio networks.

IEEE 802.11i

Standard IEEE 802.11i designed specifically to improve the security of your wireless network. For this purpose, various encryption and authentication algorithms have been created, functions are protected during information exchange, the ability to generate keys, etc.:

• AES(Advanced Encryption Standard, advanced data encryption algorithm) - an encryption algorithm that allows you to work with keys of length 128.15)2 and 256 bits;
• RADIUS(Remote Authentication Dial-In User Service) - an authentication system with the ability to generate keys for each session and manage them. including algorithms for checking the AUTHENTICITY of packages, etc.;
• TKIP(Temporal Key Integrity Protocol) - data encryption algorithm;
• WRAP(Wireless Robust Authenticated Protocol wireless protocol authentication) - data encryption algorithm;
• CCMR(Counter with Cipher Block Chaining Message Authentication Code Protocol) - data encryption algorithm.

IEEE 802.11j

Standard IEEE 802.11j designed specifically for the use of wireless networks in Japan, namely to operate in an additional radio frequency range 4.9-5 GHz. The specification is intended for Japan and expands the 802.11a standard with an additional 4.9 GHz channel.

On this moment 4.9 GHz is being considered as an additional band for use in the US. From official sources it is known that this range is being prepared for use by public and national security agencies.
This standard extends the range of operation of IEEE 802.11a standard devices.

IEEE 802.11n

Today the standard IEEE 802.11n the most common of all wireless network standards.

The 802.11n standard is based on:

• Increased data transfer speed;
• Expansion of coverage area;
• Increased signal transmission reliability;
• Increased throughput.

802.11n devices can operate in one of two bands 2.4 or 5.0 GHz.

At the physical level (PHY), improved signal processing and modulation have been implemented, and the ability to simultaneously transmit a signal through four antennas has been added.

On network level(MAC) implements more efficient use of available bandwidth. Together, these enhancements allow theoretical data transfer rates to be increased by up to 600 Mbit/s– an increase of more than ten times, compared to 54 Mbps of the 802.11a/g standard (currently these devices are already considered obsolete).

In reality, the performance of a wireless LAN depends on numerous factors such as the transmission medium, radio wave frequency, device placement and configuration.

When using 802.11n devices, it is critical to understand what improvements have been made to this standard, what they affect, and how they fit and coexist with legacy 802.11a/b/g wireless networks.

It is important to understand exactly what additional features of the 802.11n standard are implemented and supported in new wireless devices.

One of the main points of the 802.11n standard is its support for the technology MIMO(Multiple Input Multiple Output, Multi-channel input/output).
Using MIMO technology, the ability to simultaneously receive/transmit several data streams through several antennas, instead of one, is realized.

Standard 802.11n defines various antenna configurations "MxN", starting with "1x1" before "4x4"(the most common configurations today are “3x3” or “2x3”). The first number (M) determines the number of transmitting antennas, and the second number (N) determines the number of receiving antennas.

For example, an access point with two transmit and three receive antennas is "2x3" MIMO-device. I will describe this standard in more detail later.

IEEE 802.11g

Not a single wireless standard really describes the rules for roaming, that is, a client moving from one zone to another. This is what they intend to do in the standard. IEEE 802.11

IEEE 802.11ac standard

It promises gigabit wireless speeds for consumers.

Initial draft technical specification 802.11ac confirmed working group(TGac) last year. While ratification Wi-Fi Alliance expected later this year. Although the standard 802.11ac still in draft stage and still to be ratified Wi-Fi Alliance and IEEE. We are already starting to see gigabit Wi-Fi products available on the market.

Characteristics of the new generation Wi-Fi 802.11ac standard:

WLAN 802.11ac uses a range of new techniques to achieve huge performance gains while theoretically supporting gigabit potential and delivering high throughputs such as:

• 6GHz band
• High modulation density up to 256 QAM.
• Wider bandwidths - 80MHz for two channels or 160MHz for one channel.
• Up to eight Multiple Input Multiple Output spatial streams.

Low power 802.11ac multi-user MIMO poses new design challenges for engineers working with the standard. Next, we discuss these issues and the available solutions to help develop new products based on this standard.

Wider Bandwidth:

802.11ac has a wider bandwidth of 80 MHz or even 160 MHz compared to the previous up to 40 MHz in the 802.11n standard. Wider bandwidth results in improved maximum throughput for digital communications systems.

Among the most challenging design and manufacturing challenges is generating and analyzing high-bandwidth signals for 802.11ac. Testing of equipment capable of handling 80 or 160 MHz will be required to verify transmitters, receivers and components.

To generate 80 MHz signals, many RF signal generators do not have a high enough sampling rate to support the typical minimum 2X oversampling ratio that will result necessary images signals. By using proper filtering and resampling of the signal from a Waveform file, it is possible to generate 80 MHz signals with good spectral characteristics and EVM.

To generate signals 160 MHz, a wide-range arbitrary waveform generator (AWG). Such as Agilent 81180A, 8190A can be used to create analog I/Q signals.

These signals can be applied to external I/Q. As vector signal generator inputs for RF frequency conversion. In addition, it is possible to create 160 MHz signals using the 80 +80 MHz mode supporting the standard to create two 80 MHz segments in separate MCG or ESG signal generators, then combining the radio signals.

MIMO:

MIMO is the use of multiple antennas to improve the performance of a communication system. You may have seen some Wi-Fi access points that have more than one antenna. What sticks out of them - these routers use MIMO technology.

The test of MIMO designs is change. Multi-channel signal generation and analysis can be used to provide insight into the performance of MIMO devices. And providing assistance in troubleshooting and reviewing projects.

Linearity Amplifier:

The Linearity Amplifier is a characteristic and an amplifier. By which the output signal of the amplifier remains true to the input signal as it increases. In reality, linearity amplifiers are only linear up to a limit, after which the output saturates.

There are many methods to improve the linearity of an amplifier. Digital pre-emphasis is one such technique. Software design automation as SystemVue provides application. Which simplifies and automates digital pre-emphasis design for power amplifiers.

Compatible with previous versions

Although the 802.11n standard has been in use for many years. But many routers and wireless devices with older protocols still work as well. Such as 802.11b and 802.11g, although there are really few of them. Also during the transition to 802.11ac, Old Wi-Fi standards will be supported and backward compatibility will be ensured.

That's all for now. If you still have questions, feel free to write to me at,

802.11n is a data transfer mode, the real speed is approximately four times higher than that of 802.11g (54 Mbit/s). But this means if the device that sends and receives operates in 802.11n mode.

802.11n devices operate in the frequency range 2.4 - 2.5 or 5 GHz. Usually the frequency is indicated in the documentation for the device or on the packaging. Range: 100 meters (may affect speed).

IEEE 802.11n is a fast Wi-Fi operating mode, only faster than 802.11ac (this is an unrealistically cool standard). Compatibility of 802.11n with older 802.11a/b/g is possible when using the same frequency and channel.

You may think that I’m strange, but I don’t like Wi-Fi - I don’t know why, but somehow it always seems to me that it’s not as stable as wires (twisted pair). Maybe because I only had USB adapters. In the future I want to get myself a Wi-Fi PCI card, I hope that everything is stable there)) I’m already silent about the fact that Wi-Fi USB without an antenna and the speed will decrease due to any walls.. But now in our apartment the wires are lying around, and I agree - it’s not very convenient..))

As I understand it, 802.11n is a good standard, since it already includes the characteristics of 802.11a/b/g.

However, it turns out that 802.11n is not compatible with previous standards. And as I understand it, this is the main reason why 802.11n is still not a very popular standard, but it appeared in 2007. It seems that there is still compatibility - I wrote about it below.

Some characteristics of other standards:

There are many standards and some of them are very interesting for their purpose:

Look, 802.11p determines the type of devices that, within a kilometer radius, travel at a speed of no more than 200 km... can you imagine?)) This is technology!!

802.11n and router speed

Look, there may be such a situation - you need to increase the speed in the router. What to do? Your router can easily support the IEEE 802.11n standard. You need to open the settings, and somewhere there find the option to use this standard, that is, for the device to operate in this mode. If you have an ASUS router, then the setting may look something like this:

In fact, the main thing is the letter N. If you have a TP-Link company, then the setting may look like this:

That's all for the router. I understand that there is not enough information - but at least now you know that the router has such a setting, but how to connect to the router... it’s better to look on the Internet, I admit - I’m not good at this. I just know that I need to open the address.. something like 192.168.1.1, something like that..

If you have a laptop, it may also support the IEEE 802.11n standard. And it is useful to install it if, for example, you create an access point from a laptop (yes, this is possible). Open Device Manager by holding down the Win + R buttons and paste this command:

Then find your Wi-Fi adapter (may be called network adapter Broadcom 802.11n) - Right-click and select Properties:

Go to the Advanced tab and find the 802.11n Direct Connection Mode item, select enable:

The setting may be called differently - Wireless Mode, Wireless Type, Wi-Fi Mode, Wi-Fi type. In general, you need to specify the data transfer mode. But the effect in terms of speed, as I already wrote, will be provided that both devices use the 802.11n standard.

I found this important information regarding compatibility:

About compatibility, and also a lot important information Read about 802.11 standards here:

There really is a lot of valuable information there, I advise you to take a look.

AdHoc Support 802.11n what is it? Should I turn it on or not?

AdHoc Support 802.11n or AdHoc 11n - support for temporary AdHoc network operation when connection is possible between different devices. Used for online data transfer. I couldn’t find any information about whether it is possible to organize Internet distribution on the AdHoc network (but anything is possible).

Officially, AdHoc limits the speed to the level of the 11g standard - 54 Mbit/s.

I learned an interesting point - the speed of Wi-Fi 802.11g, as I already wrote, is 54 Mbit/s. However, it turns out that 54 is a total figure, that is, it is reception and sending. So, one way speed is 27 Mbit/s. But that’s not all - 27 Mbit/s is a channel speed that is possible under ideal conditions, it is unrealistic to achieve them - 30-40% of the channel is still interference in the form mobile phones, all sorts of radiation, smart TVs with Wi-Fi and so on. As a result, the speed in reality can actually be 18-20 Mbit/s, or even less. I will not say - but it is possible that this also applies to other standards.

So should I turn it on or not? It turns out that if there is no need, there is no need. Also, if I understand correctly, when turned on, a new local network will be created and perhaps it is still possible to organize the Internet in it. In other words, it may be... that using AdHoc you can create a point Wi-Fi access. I just looked it up on the Internet - it seems possible))

I just remember this... once I bought myself a Wi-Fi adapter from D-Link (I think it was the D-Link N150 DWA-123 model) and there was no support for creating an access point. But here’s the chip, it was either Chinese... or something else... in general, I found out that you can install special unofficial drivers on it, semi-curve ones, and with the help of them you can create an access point.. And this point access seemed to work using AdHoc, unfortunately I don’t remember exactly - but it worked more or less tolerably.

Ad Hoc settings in network card properties

Note - QoS is a technology for distributing traffic in terms of priorities. Provides the required high level of packet transmission for important processes/programs. If in simple words, then QoS allows you to set high priority to programs that require instant data transfer - Online Games, VoIP telephony, streaming, streaming and the like probably also applies to Skype and Viber.

802.11 Preamble Long and Short - what is this setting?

Yes, these settings are a whole science. The part of the frame that is transmitted by the 802.11 module is called the preamble. There can be a long (Long) and a short (Short) preamble, and apparently this is indicated in the 802.11 Preamble (or Preamble Type) setting. The long preamble uses a 128-bit synchronization field, the short one uses a 56-bit.

802.11 devices operating at the 2.4 GHz frequency are required to support long preambles when receiving and transmitting. 802.11g devices must be able to handle long and short preambles. In 802.11b devices, short preambles are optional.

The values ​​in the 802.11 Preamble setting can be Long, Short, Mixed mode, Green field, Legacy mode. I’ll say right away - it’s better not to touch these settings unless necessary and leave the default value or, if available, select Auto (or Default).

We have already found out above what the Long and Short modes mean. Now briefly about other modes:

1. Legacy mode. Data exchange mode between stations with one antenna.
2. Mixed mode. Data transfer mode between MIMO systems (fast, but slower than Green field), and between conventional stations (slow, since they do not support high speeds). The MIMO system determines the packet depending on the receiver.
3. Green field. Transmission is possible between multi-antenna devices. When a MIMO transmission occurs, conventional stations wait for the channel to become free to avoid collisions. In this mode, receiving data from devices operating in the above two modes is possible, but transmitting data to them is not. This is done to eliminate single-antenna devices during data transmission, thereby maintaining high transmission speeds.

MIMO support what is it?

On a note. MIMO (Multiple Input Multiple Output) is a type of data transmission in which the channel is increased using spatial signal coding and data transmission is carried out by several antennas simultaneously.

The IEEE (Institute of Electrical and Electronic Engineers) is developing WiFi 802.11 standards.

IEEE 802.11 is the base standard for Wi-Fi networks, which defines a set of protocols for the lowest data transfer rates (transfer).

IEEE 802.11b- describes b O higher transmission speeds and introduces more technological restrictions. This standard was widely promoted by WECA ( Wireless Ethernet Compatibility Alliance ) and was originally called WiFi .
Frequency channels in the 2.4GHz spectrum are used ().
Ratified in 1999.
RF technology used: DSSS.
Coding: Barker 11 and CCK.
Modulations: DBPSK and DQPSK,
Maximum data transfer rates (transfer) in the channel: 1, 2, 5.5, 11 Mbps,

IEEE 802.11a- describes significantly higher transfer rates than 802.11b.
Frequency channels in the 5GHz frequency spectrum are used. ProtocolNot compatible with 802.11 b.
Ratified in 1999.
RF technology used: OFDM.
Coding: Conversion Coding.
Modulations: BPSK, QPSK, 16-QAM, 64-QAM.
Maximum data transfer rates in the channel: 6, 9, 12, 18, 24, 36, 48, 54 Mbps.

IEEE 802.11g - describes data transfer rates equivalent to 802.11a.
Frequency channels in the 2.4GHz spectrum are used. The protocol is compatible with 802.11b.
Ratified in 2003.
RF technologies used: DSSS and OFDM.
Coding: Barker 11 and CCK.
Modulations: DBPSK and DQPSK,
Maximum data transfer rates (transfer) in the channel:
- 1, 2, 5.5, 11 Mbps on DSSS and
- 6, 9, 12, 18, 24, 36, 48, 54 Mbps on OFDM.

IEEE 802.11n- the most advanced commercial WiFi standard, currently officially approved for import and use in the Russian Federation (802.11ac is still being developed by the regulator). 802.11n uses frequency channels in the 2.4GHz and 5GHz WiFi frequency spectrums. Compatible with 11b/11 a/11g . Although it is recommended to build networks targeting only 802.11n, because... requires configuration of special protective modes if backward compatibility with legacy standards is required. This leads to a large increase in signal information anda significant reduction in the available useful performance of the air interface. Actually, even one WiFi 802.11g or 802.11b client will require special configuration of the entire network and its immediate significant degradation in terms of aggregated performance.
The WiFi 802.11n standard itself was released on September 11, 2009.
Frequencies supported WiFi channels width 20MHz and 40MHz (2x20MHz).
RF technology used: OFDM.
OFDM MIMO (Multiple Input Multiple Output) technology is used up to the 4x4 level (4xTransmitter and 4xReceiver). In this case, a minimum of 2xTransmitter per Access Point and 1xTransmitter per user device.
Examples of possible MCS (Modulation & Coding Scheme) for 802.11n, as well as the maximum theoretical transfer rates in the radio channel are presented in the following table:

Here SGI is the guard intervals between frames.
Spatial Streams is the number of spatial streams.
Type is the modulation type.
Data Rate is the maximum theoretical data transfer rate in the radio channel in Mbit/sec.

It is important to emphasize that the indicated speeds correspond to the concept of channel rate and are the maximum value using a given set of technologies within the framework of the described standard (in fact, these values, as you probably noticed, are written by manufacturers on the boxes of home WiFi devices in stores). But in real life, these values ​​are not achievable due to the specifics of the WiFi 802.11 standard technology itself. For example, “political correctness” is strongly influenced here in terms of ensuring CSMA/CA ( WiFi devices constantly listen to the air and cannot transmit if the transmission medium is busy), the need to acknowledge each unicast frame, the half-duplex nature of all WiFi standards and only 802.11ac/Wave-2 can begin to bypass this, etc. Therefore, the practical effectiveness of outdated 802.11 standards b/g/a never exceeds 50% under ideal conditions (for example, for 802.11g the maximum speed per subscriber is usually no higher than 22Mb/s), and for 802.11n the efficiency can be up to 60%. If the network operates in protected mode, which often happens due to the mixed presence of different WiFi chips on different devices on the network, then even the indicated relative efficiency can drop by 2-3 times. This applies, for example, to a mix of Wi-Fi devices with 802.11b, 802.11g chips on a network with WiFi 802.11g access points, or a WiFi 802.11g/802.11b device on a network with WiFi 802.11n access points, etc. Read more about .

In addition to the basic WiFi standards 802.11a, b, g, n, additional standards exist and are used to implement various service functions:

. 802.11d. To adapt various WiFi standard devices to specific country conditions. Within the regulatory framework of each state, ranges often vary and may even differ depending on geographic location. IEEE 802.11d WiFi standard allows adjustment of frequency bands in devices different manufacturers using special options introduced into the media access control protocols.

. 802.11e. Describes QoS quality classes for the transmission of various media files and, in general, various media content. Adaptation of the MAC layer for 802.11e determines the quality, for example, of simultaneous transmission of audio and video.

. 802.11f. Aimed at unifying the parameters of Wi-Fi access points from different manufacturers. The standard allows the user to work with different networks when moving between coverage areas of individual networks.

. 802.11h. Used to prevent problems with weather and military radars by dynamically reducing the emitted power of Wi-Fi equipment or dynamically switching to another frequency channel when a trigger signal is detected (in most European countries, ground stations tracking weather and communications satellites, as well as military radars operate in ranges close to 5 MHz). This standard is a necessary ETSI requirement for equipment approved for use in the European Union.

. 802.11i. The first iterations of the 802.11 WiFi standards used the WEP algorithm to secure Wi-Fi networks. It was believed that this method could provide confidentiality and protection of the transmitted data of authorized wireless users from eavesdropping. Now this protection can be hacked in just a few minutes. Therefore, the 802.11i standard developed new methods for protecting Wi-Fi networks, implemented at both the physical and software levels. Currently, to organize a security system in Wi-Fi 802.11 networks, it is recommended to use Wi-Fi Protected Access (WPA) algorithms. They also provide compatibility between wireless devices various standards and various modifications. WPA protocols use an advanced RC4 encryption scheme and a mandatory authentication method using EAP. The stability and security of modern Wi-Fi networks is determined by privacy verification and data encryption protocols (RSNA, TKIP, CCMP, AES). The most recommended approach is to use WPA2 with AES encryption (and don't forget about 802.1x using tunneling mechanisms, such as EAP-TLS, TTLS, etc.). .

. 802.11k. This standard is actually aimed at implementing load balancing in the radio subsystem of a Wi-Fi network. Typically, in a wireless LAN, the subscriber device usually connects to the access point that provides the strongest signal. This often leads to network congestion at one point, when many users connect to one Access Point at once. To control such situations, the 802.11k standard proposes a mechanism that limits the number of subscribers connected to one Access Point and makes it possible to create conditions under which new users will join another AP even despite a weaker signal from it. In this case, the aggregated network throughput increases due to more efficient use of resources.

. 802.11m. Amendments and corrections for the entire group of 802.11 standards are combined and summarized in a separate document under the general name 802.11m. The first release of 802.11m was in 2007, then in 2011, etc.

. 802.11p. Determines the interaction of Wi-Fi equipment moving at speeds up to 200 km/h past fixed points WiFi access, located at a distance of up to 1 km. Part of the Wireless Access in Vehicular Environment (WAVE) standard. WAVE standards define the architecture and additional set utility functions and interfaces that provide a secure radio communication mechanism between moving vehicles. These standards are designed for applications such as traffic management, traffic safety monitoring, automated toll collection, navigation and routing. Vehicle and etc.

. 802.11s. A standard for implementing mesh networks (), where any device can serve as both a router and an access point. If the nearest access point is overloaded, data is redirected to the nearest unloaded node. In this case, a data packet is transferred (packet transfer) from one node to another until it reaches its final destination. This standard introduces new protocols at the MAC and PHY levels that support broadcast and multicast (transfer), as well as unicast delivery over a self-configuring Wi-Fi access point system. For this purpose, the standard introduced a four-address frame format. Implementation examples WiFi networks Mesh: , .

. 802.11t. The standard was created to institutionalize the process of testing solutions of the IEEE 802.11 standard. Testing methods, methods of measurement and processing of results (treatment), requirements for testing equipment are described.

. 802.11u. Defines procedures for interaction of Wi-Fi standard networks with external networks. The standard must define access protocols, priority protocols and prohibition protocols for working with external networks. At the moment, a large movement has formed around this standard, both in terms of developing solutions - Hotspot 2.0, and in terms of organizing inter-network roaming - a group of interested operators has been created and is growing, who jointly resolve roaming issues for their Wi-Fi networks in dialogue (WBA Alliance ). Read more about Hotspot 2.0 in our articles: , .

. 802.11v. The standard should include amendments aimed at improving the network management systems of the IEEE 802.11 standard. Modernization at the MAC and PHY levels should allow the configuration of client devices connected to the network to be centralized and streamlined.

. 802.11y. Additional communication standard for the frequency range 3.65-3.70 GHz. Designed for the latest generation devices working with external antennas at speeds up to 54 Mbit/s at a distance of up to 5 km in open space. The standard is not fully completed.

802.11w. Defines methods and procedures for improving the protection and security of the media access control (MAC) layer. The standard protocols structure a system for monitoring data integrity, the authenticity of their source, the prohibition of unauthorized reproduction and copying, data confidentiality and other protection measures. The standard introduces management frame protection (MFP: Management Frame Protection), and additional security measures help neutralize external attacks, such as DoS. A little more on MFP here: . In addition, these measures will ensure security for the most sensitive network information that will be transmitted over networks that support IEEE 802.11r, k, y.

802.11ac. A new WiFi standard that operates only in the 5GHz frequency band and provides significantly faster O higher speeds both for an individual WiFi client and for a WiFi Access Point. See our article for more details.

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Protocol wireless communication Wi-Fi (Wireless Fidelity) was developed back in 1996. It was originally intended to build local networks, but gained the greatest popularity as effective method Internet connections of smartphones and other portable devices.

Over the course of 20 years, the alliance of the same name has developed several generations of the connection, introducing faster and more functional updates every year. They are described by 802.11 standards published by the IEEE (Institute of Electrical and Electronics Engineers). The group includes several versions of the protocol, differing in data transfer speed and support for additional functions.

The very first Wi-Fi standard did not have letter designation. Devices that support it communicate at a frequency of 2.4 GHz. The information transfer speed was only 1 Mbit/s. There were also devices that supported speeds of up to 2 Mbit/s. It was actively used for only 3 years, after which it was improved. Each subsequent Wi-Fi standard is designated by a letter after the common number (802.11a/b/g/n, etc.).

One of the first updates to the Wi-Fi standard, released in 1999. By doubling the frequency (up to 5 GHz), engineers were able to achieve theoretical speeds of up to 54 Mbit/s. It was not widely used, since it itself is incompatible with other versions. Devices that support it must have a dual transceiver to operate on 2.4 GHz networks. Smartphones with Wi-Fi 802.11a are not widespread.

Wi-Fi standard IEEE 802.11b

The second early interface update, released in parallel with version a. The frequency remained the same (2.4 GHz), but the speed was increased to 5.5 or 11 Mbit/s (depending on the device). Until the end of the first decade of the 2000s, it was the most common standard for wireless networks. Compatible with more old version, as well as a fairly large coverage radius, ensured its popularity. Despite being superseded by new versions, 802.11b is supported by almost all modern smartphones.

Wi-Fi standard IEEE 802.11g

A new generation of Wi-Fi protocol was introduced in 2003. The developers left the data transmission frequencies the same, making the standard fully compatible with the previous one (old devices operated at speeds of up to 11 Mbit/s). The information transfer speed has increased to 54 Mbit/s, which was sufficient until recently. All modern smartphones work with 802.11g.

Wi-Fi standard IEEE 802.11n

In 2009, a large-scale update to the Wi-Fi standard was released. A new version interface received a significant increase in speed (up to 600 Mbit/s), while maintaining compatibility with previous ones. To be able to work with 802.11a equipment, as well as combat congestion in the 2.4 GHz band, support for 5 GHz frequencies has been returned (parallel to 2.4 GHz).

Network configuration options have been expanded and the number of simultaneously supported connections has been increased. It has become possible to communicate in multi-stream MIMO mode (parallel transmission of several data streams on the same frequency) and combine two channels for communication with one device. The first smartphones supporting this protocol were released in 2010.

Wi-Fi standard IEEE 802.11ac

In 2014, a new Wi-Fi standard, IEEE 802.11ac, was approved. It became a logical continuation of 802.11n, providing a tenfold increase in speed. Thanks to the ability to combine up to 8 channels (20 MHz each) simultaneously, the theoretical ceiling has increased to 6.93 Gbit/s. which is 24 times faster than 802.11n.

It was decided to abandon the 2.4 GHz frequency due to the congestion of the range and the impossibility of combining more than 2 channels. The IEEE 802.11ac Wi-Fi standard operates in the 5 GHz band and is backward compatible with 802.11n (2.4 GHz) devices, but works with more earlier versions not guaranteed. Today, not all smartphones support it (for example, many budget smartphones on MediaTek do not have support).

Other standards

There are versions of IEEE 802.11 labeled with different letters. But they either make minor amendments and additions to the standards listed above, or add specific functions (such as the ability to interact with other radio networks or security). It is worth highlighting 802.11y, which uses a non-standard frequency of 3.6 GHz, as well as 802.11ad, designed for the 60 GHz range. The first is designed to provide a communication range of up to 5 km, through the use of pure range. The second (also known as WiGig) is designed to provide maximum (up to 7 Gbit/s) communication speed over ultra-short distances (within a room).

Which Wi-Fi standard is better for a smartphone?

All modern smartphones are equipped with a Wi-Fi module designed to work with several versions of 802.11. In general, all mutually compatible standards are supported: b, g and n. However, work with the latter can often be realized only at a frequency of 2.4 GHz. Devices that are capable of operating on 5 GHz 802.11n networks also feature support for 802.11a as backwards compatible.

An increase in frequency helps to increase the speed of data exchange. But at the same time, the wavelength decreases, making it more difficult for it to pass through obstacles. Because of this, the theoretical range of 2.4 GHz will be higher than 5 GHz. However, in practice the situation is a little different.

The 2.4 GHz frequency turned out to be free, so consumer electronics use it. In addition to Wi-Fi, Bluetooth devices and transceivers operate in this range wireless keyboards and mice, it also emits magnetrons from microwave ovens. Therefore, in places where several Wi-Fi networks operate, the amount of interference offsets the range advantage. The signal will be caught even from a hundred meters away, but the speed will be minimal, and the loss of data packets will be large.

The 5 GHz band is wider (from 5170 to 5905 MHz) and less congested. Therefore, waves are less able to overcome obstacles (walls, furniture, human bodies), but in direct visibility conditions they provide a more stable connection. The inability to effectively overcome walls turns out to be an advantage: you won’t be able to catch your neighbor’s Wi-Fi, but it won’t interfere with your router or smartphone.

However, it should be remembered that to achieve maximum speed, you also need a router that works with the same standard. In other cases, you still won’t be able to get more than 150 Mbit/s.

Much depends on the router and its antenna type. Adaptive antennas are designed in such a way that they detect the location of the smartphone and send it a directional signal that reaches further than other types of antennas.

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If you're looking for the fastest WiFi, you need 802.11ac, it's as simple as that. Essentially, 802.11ac is an accelerated version of 802.11n (the current WiFi standard used on your smartphone or laptop), offering link speeds ranging from 433 megabits per second (Mbps), up to several gigabits per second. To achieve speeds that are tens of times faster than 802.11n, 802.11ac operates exclusively in the 5GHz band, uses huge bandwidth (80-160MHz), works with 1-8 spatial streams (MIMO), and uses a peculiar technology called "beamforming" (beamforming). additional information about what 802.11ac is and how it will eventually replace wired gigabit Ethernet home and work network, we'll talk further.

How 802.11ac works.

A few years ago, 802.11n introduced some interesting technology that significantly increased speed compared to 802.11b and g. 802.11ac works almost the same as 802.11n. For example, while the 802.11n standard supported up to 4 spatial streams, and a channel width of up to 40 MHz, 802.11ac can use 8 channels, and a width of up to 80 MHz, and combining them can generally produce 160 MHz. Even if everything else remained the same (and it won't), this means that 802.11ac handles 8x160MHz spatial streams, compared to 4x40MHz. A huge difference that will allow you to squeeze huge amounts of information out of radio waves.

To improve throughput even further, 802.11ac also introduced 256-QAM modulation (compared to 802.11n's 64-QAM), which literally compresses 256 different signals of the same frequency, shifting and interweaving each one into a different phase. Theoretically, this increases the spectral efficiency of 802.11ac by 4 times compared to 802.11n. Spectral efficiency is a measure of how well a wireless protocol or multiplexing technique uses the bandwidth available to it. In the 5GHz band, where the channels are quite wide (20MHz+), spectral efficiency is not so important. In the cellular bands, however, channels are most often 5 MHz wide, making spectral efficiency extremely important.

802.11ac also introduces standardized beamforming (802.11n had it but was not standardized, making interoperability an issue). Beamforming essentially transmits radio signals in such a way that they are aimed at specific device. This can improve overall throughput and make it more consistent, as well as reduce power consumption. Beam shaping can be done by using a smart antenna that physically moves in search of the device, or by modulating the amplitude and phase of the signals so that they destructively interfere with each other, leaving a narrow, non-interfering beam. 802.11n uses the second method, which can be used by both routers and mobile devices. Finally, 802.11ac, like previous versions 802.11 is fully backward compatible with 802.11n and 802.11g, so you can buy an 802.11ac router today and it will work great with your older WiFi devices.

802.11ac range

Theoretically, at 5 MHz and using beamforming, 802.11ac should have the same or better range than 802.11n (beamforming white). The 5 MHz band, due to its lower penetrating power, does not have the same range as 2.4 GHz (802.11b/g). But that's a trade-off we're forced to make: we simply don't have enough spectral bandwidth in the heavily used 2.4GHz band to allow 802.11ac's peak gigabit-level speeds. As long as your router is in the perfect location, or you have several of them, there is no need to worry. As always, the more important factor is the power transmission of your devices, and the quality of the antenna.

How fast is 802.11ac?

And finally, the question everyone wants to know: how fast is 802.11ac WiFi? As always, there are two answers: the speed theoretically achievable in the lab, and the practical speed limit you'll likely be content with in a real-world home environment surrounded by a bunch of signal-jamming obstacles.

The theoretical maximum speed of 802.11ac is 8 channels of 160MHz 256-QAM, each capable of 866.7Mbps, giving us 6.933Mbps, or a modest 7Gbps. Transfer speed of 900 megabytes per second is faster than transfer to a SATA 3 drive. In the real world, due to channel clogging, you most likely will not get more than 2-3 160 MHz channels, so the maximum speed will stop somewhere at 1.7-2.5 Gbit/s. Compared to 802.11n's theoretical maximum speed of 600Mbps.

Apple Airport Extreme at 802.11ac, disassembled by iFixit today's most powerful router (April 2015), includes D-Link AC3200 Ultra Wi-Fi Router (DIR-890L/R), Linksys Smart Wi-Fi Router AC 1900 (WRT1900AC), and Trendnet AC1750 Dual-Band Wireless Router (TEW-812DRU), as reported by PCMag. With these routers, you can definitely expect impressive speeds from 802.11ac, but don't bite off your Gigabit Ethernet cable just yet.

In Anandtech's 2013 test, they tested a WD MyNet AC1300 802.11ac router (up to three streams) paired with a number of 802.11ac devices that supported 1-2 streams. Fastest transfer speed has been achieved Intel laptop 7260 with an 802.11ac wireless adapter that used two streams to achieve 364Mbps over a distance of just 1.5m. At 6m and through the wall, the same laptop was the fastest, but the maximum speed was 140Mb/s. The fixed speed limit for the Intel 7260 was 867Mb/s (2 streams of 433Mb/s).

In a situation where you don't need maximum performance and the reliability of wired GigE, 802.11ac is truly compelling. Instead of cluttering your living room with an Ethernet cable running to your home theater from your PC under your TV, it makes more sense to use 802.11ac, which has enough throughput to deliver high-definition wireless content to your HTPC. For all but the most demanding cases, 802.11ac is a very worthy replacement for Ethernet.

The future of 802.11ac

802.11ac will become even faster. As we mentioned earlier, the theoretical maximum speed of 802.11ac is a modest 7Gbps, and until we hit that in the real world, don't be surprised by the 2Gbps mark in the next few years. At 2Gbps, you get 256Mbps transfer speeds, and suddenly Ethernet will be used less and less until it disappears. To achieve such speeds, chipset and device manufacturers will have to figure out how to implement four or more channels for 802.11ac, given how software, and hardware.

We see Broadcom, Qualcomm, MediaTek, Marvell and Intel already making strong moves to provide 4-8 channels for 802.11ac to integrate the latest routers, access points, and mobile devices. But until the 802.11ac specification is finalized, a second wave of chipsets and devices is unlikely to appear. Device and chipset manufacturers will have a lot of work to do to ensure that advanced technologies like beamforming are compliant with the standard and are fully compatible with other 802.11ac devices.